As explained in many other threads, GSX jetway replacement should only be used on DEFAULT airports, and if you have a 3rd party airport, it should always be Disabled in the GSX Config panel.
This is not dependent by the addon usage of the default Asobo model, because we don't replace that one.
The issue is, jetway replacement in GSX is not made by replacing the Asobo model but, instead, through a set of pre-made 918 .BGL files, which replace jetways individually for each default airport that had a jetway in the default scenery, that's the only way to have individual jetway models, instead of a "changed" Asobo model that would have look identical everywhere.
The reason why these Jetway replacement files only work with default airports, is because jetways are associated with a specific parking spot (otherwise they won't work ) so, if you have a 3rd party airport that will likely have different parking spots, possibly named differently and in different positions compared to default, having the GSX replacement file active will cause problems like not working jetways or double parking spots in the Map.
That's why the GSX installer will automatically look for 3rd party airports in the Community folder and will Disable them automatically, provided their package matches the standard developer-airport-ICAO-name naming convention, and will do that every time you run an update.
If you have a scenery whose package doesn't match that naming standard, or you never ran the FSDT Update after you installed it, the GSX Jetway replacement file won't be added to the Disabled list, so you will see GSX Jetways there, but that doesn't mean it's a good idea to do so because, while they will surely look better than default, they won't likely work, either because their position changed, but more likely because the parking names might have changed.
Basically, unless you have a very rare situation of a 3rd party airport that has parking spots named *exactly* and in the *same* position as the default one, with its own jetways ( custom or default, doesn't really matter ) placed in *exactly* the same position as the default one, you should always Disable the GSX Replacement file.
